The present invention concerns a process and a device for counterbalancing the inertia forces in a rotary machine comprising at least one piston axially movable in a cylinder, such as a heat engine, and each cylinder of which is fitted with at least one rotating intake and/or exhaust distributor.
In reciprocating piston machines such as internal combustion engines or compressors, the forces due to the pressures of the gases in the combustion chamber as well as the inertia forces corresponding to the movement of the mobile elements such as pistons, connecting rods, cranks, crankshafts are continuously variable throughout the rotation cycle.
Although the compression forces may be counterbalanced in the frame or body of a motor this is not the case of the forces which are transmitted to the motor body and must be, if not removed, at least considerably reduced, in order to ensure a rotation of the motor that does not interfere too much with its surroundings by transmitting the vibrations caused by its rotation and does not risk prematurely wearing out the motor and its attachments to a support element such as a vehicle.
In order to limit the vibrations of the piston machines caused by their own rotation, it is known to compensate the irregular distribution of the masses about the axis of rotation by counterweights principally provided on the crankshaft of the motor, opposite facing, with respect to the axis of rotation of the crankshaft, to the crank of the piston and to the connecting rod and piston that are pivotally connected to it. Such a counter balancing is always difficult since the size and the position of the counterweights can often only be exactly determined by successive experimentations, and, furthermore, the counterweights cannot always be easily housed in the crankcase of the machine.
Such a situation is to be found, especially, in monocylindrical motors or compressors where thhe crank connecting the rod to the crankshaft must present a maximal stiffness with very bulky bearings, such as roller bearings, that practically prohibit housing in the crankcase counterweights of a volume sufficient to counterbalance the unbalance equivalent with the elbow of the crankshaft and the connecting rod that it supports.
One of the aims of the present invention is precisely to allow to reduce the bulkiness of the compensating counterweights housed in the sealed crankcase of the crankshaft by utilizing, as counterweight supports, rotating elements mechanically connected to this crankshaft.